Quantitative Regulation of Recrystallization Behavior and Grain Boundary Characteristics of Stainless Steel Ultra-Thin Strips by Electrical Pulse Treatment

To reveal the effects of electrical pulse treatment parameters and initial deformation states on the recrystallization behavior and grain boundary characteristics of SUS304 stainless steel ultra-thin strips, electrical pulse treatments were systematically conducted by varying current density (1.50–1.80 A·mm−2), pulse frequency (50–3000 Hz), duty cycle (5–20%), and treatment duration (5–20 s) under their respective controlled conditions. Electron backscatter diffraction (EBSD) was employed to analyze the evolution of recrystallized fraction, local misorientation, grain boundary types, and Σ3n special grain boundaries. The results demonstrate that electric pulse treatment significantly promotes recovery and recrystallization of cold-rolled microstructures, while current density, pulse frequency, and duty cycle exhibit distinct sensitivity windows. Specimens with higher initial deformation levels show stronger dislocation recovery and recrystallization responses under identical electric pulse treatment conditions. Furthermore, based on the classical Johnson–Mehl–Avrami–Kolmogorov (JMAK) model, a semi-empirical prediction model for static recrystallization fraction was established by incorporating electric pulse treatment parameters and initial geometrically necessary dislocation (GND) density, achieving a coefficient of determination, R2, of 0.9545. Quantitative correlations between recrystallized fraction and high-angle grain boundaries (HAGBs) and low-angle grain boundaries (LAGBs) as well as Σ3n special grain boundaries were further established. This work provides new insights into the quantitative control of recrystallization behavior and grain boundary evolution in ultra-thin metallic strips through electric pulse treatment.